1. Field of the Invention
In traveling wave tubes, a beam of electrons is caused to interact with a propagating electromagnetic energy wave. The interaction amplifies the electromagnetic energy wave. In order to achieve the desired interaction, a slow wave structure is used as a path of propagation for the electromagnetic energy wave. The slow wave structure, which is generally helical in arrangement, winds about the path of the electron beam. A novel slow wave structure is the subject of the present invention.
2. Description of the Prior Art
In general, slow wave structures are common in the prior art. More particularly, a slow wave structure comprises an internal helical slow wave structure, a generally tubular external wall which surrounds the helical structure, and support members which are interposed between the external wall and the helical structure. Support members are necessary as heat conduction paths and mechanical supports. For example, support rods are disclosed in U.S. Pat. No. 3,895,326, by Hinckeledy et al., U.S. Pat. No. 4,158,791, by Lien et al., and U.S. Pat. No. 4,278,914, by Harper. In addition, ceramic or dielectric material support members are disclosed in U.S. Pat. No. 3,903,449, by Scott et al., U.S. Pat. No. 4,093,892, by Vanderplaats, and U.S. Pat. No. 4,115,721, by Friz. However, slow wave structures having ceramic or dielectric material support members in the prior art are deficient in several aspects.
One deficiency in the prior art is the inability of prior art structures to have increased interaction operating efficiency.
Another deficiency in the prior art is the inability of prior art slow wave structures to have wider bandwidth.